So? It's not your box. Does that somehow mean rm -rf * won't work? You still lose your files, you lose the resource, and unless the admin of the box is nicer than I am about such things - doubtful, btw - you'll really piss them off, too.
I read your node. You advocated a dangerous method of trying to protect your files. I understand wanting to protect them, especially if they had some commercial purpose. But this was not your box; therefore, the owner/admin sets the rules. If you were paying for the shell access, then the rules for accessing your files should be spelled out in the contract; if it was a guest or quid pro quo account, which you seem to imply, then you have no rights or privelages beyond what the admin grants you. By the same token, the admin is the one responsible for the security of the box, not you. Installing any application, and especially a security application, without notifying the admin is at the least bad manners and will quite possibly get you kicked off the box.
If you have a security problem on a public box, step one should be to contact the admin, not firing up emacs. Step two, if step one fails for some reason, should be to use a product that already exists if possible; it's far less likely to cause a problem than quickly written code, especially if you are not an experienced security admin. Step three, if that is not possible or if it fails to stop the problem, should be to pull everything off the box and quit using that account. In fact, I'm tempted to make that step two. The LAST resort, and I mean absolute LAST, is to write something like what you did here; and it should NEVER tell the intruder that they've been detected.
- email Ozymandias